As work continues on the production of a sodium sulfur battery which can be used in commercial applications, many problems are encountered which must be solved in order to make such a battery a cost effective energy system competitive with present day energy systems.
The method taught in this specification is one which provides for a most cost effective assembly of the various components of the battery. By a more cost effective assembly, I mean that the assembly operation does not have to be carried out in its entirety under a protective atmosphere, thereby reducing the cost associated with such assembly as well as the complexity thereof.
The method taught is this specification is also one which provides for an efficient starting of the reactive capability of the battery when assembled. The reactive capability is brought about by heating the assembled battery to an operational temperature. When the method of assembly taught in this specification is employed, the starting capabilities of the battery are greatly enhanced in that the battery normally starts functioning in its intended manner within a few hours after reaching an operational temperature.
It is a principal object of this invention to provide a method of forming a sodium sulfur battery which is more cost effective and a method which provides for a starting of the reactive capability of an assembly battery within a relatively short time after reaching an operational temperature.
U.s. Pat. No. 4,102,042 issued on July 25, 1978 to Steven A. Weiner for a "Method for Preparing a sodium Sulfur Cell" is the prior art I consider most relevant. This patent shows a method of assembling a sodium sulfur cell in which the cathodic reaction zone of the cell is prepared in air. After the preparation of the cathodic reaction zone, that sub-assembly is removed into an inert atmosphere such as argon. After the removal of the assembly into the inert atmosphere, a precast sodium slug is inserted into a safety sleeve of the battery and a cylindrical sodium container portion is placed thereover. The sodium and sulfur containers are then mechanically sealed while the entire cell remains in the inert atmosphere. The cell thus remains in the inert atmosphere during the assembly of the cell components and the sealing thereof. Such assembly techniques are expensive because of the requirement of handling the cell while in an inert atmosphere.
U.S. Pat. No. 4,011,366 issued on Mar. 8, 1977 to Bones et al for "Electric Cell" also discloses technology relating to a sodium sulfur cell. Briefly, this patent shows a circuit breaker device responsive to temperature or current. This circuit breaker device is inserted inside the cell in series in the internal electric circuit of the cell. The purpose of this circuit breaker device is to open the circuit in the cell in the event of either an abnormal cell temperature or current. The circuit breaking device may be in the form of a fusible metal length or a temperature sensitive switch.